1. Field of the Invention
This invention relates to current detection methods and circuits for detecting currents flowing through switching transistors arranged in outputs of pulse-width modulation (PWM) amplifiers, which are provided for LSI chips and ICs. In addition, this invention also relates to overcurrent protection against abnormally high currents flowing through switching transistors of PWM amplifiers.
2. Description of the Related Art
It is necessary to detect currents flowing through switching transistors arranged at outputs of switching circuits such as PWM amplifiers, which are provided for LSI chips and ICs. The current detection is realized by inserting resistors in series to switching transistors. Alternatively, the current detection is realized by using wiring resistances of ICs.
However, the current detection must conventionally cause power loss because of the use of the ‘current detecting’ resistors. Even though the current detection is realized using wiring resistances of ICs, it is very difficult to accurately perform current detection because wiring resistances cannot be always defined with a good accuracy because of dispersions of dimensions of wires.